Design and Assembly of mini tractor
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DESIGN AND MODELLING OF MINI ELECTRIC TRACTOR
INDEPENDENT PROJECT
Objective:
To design and model the mini tractor.
Software used:
Solid-works.
Abstract:
The main purpose of this project is to know how much knowledge I have gained in SolidWorks tool, I have used both surface and solid modelling in this project.
The properties of the project like application of material are just assumed as of the real world.
Introduction:
The word “tractor” is related to words like “traction” and “tractive,” from the Latin word “tractus” meaning drawing (pulling): a tractor is essentially a machine designed to pull things along, usually very slowly and surely.
A tractor is an engineering vehicle specifically designed to deliver a high tractive effort or torque at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture. Most commonly, the term is used to describe a farm vehicle that provides the power and traction to mechanize agricultural tasks, especially (and originally) tillage, but nowadays a great variety of tasks. Agricultural implementations may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised.
As of now, tractors run on liquid fuels which consume lot of fuel and it also affects the pollution so also we are running out of fossil fuels.
So, I have designed a mini tractor which can run on electrical energy and it is of compact and simple design.
Design:
CHASSIS:
A chassis is the load-bearing framework of an artificial object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpart of a motor vehicle, on which the body is mounted; if the running- gear such as wheels and transmission, and sometimes even the driver's seat, are included, then the assembly is described as a rolling chassis.
The chassis I have designed have seat included in it and also rear indicators.
Also, I have added cup holders to the seat itself.
commands used: Sketch, Boss extrude, Mirror(for symmetry), Cut extrude, Fillet(for sharp edges), Split line, Shell(for hallow frame) and Chamfer.
MOTOR:
Motor is designed to convert one form of energy to another form here it is used to convert the electric energy of the batteries to mechanical energy to run the wheels.
Motor consists of several parts they are
Front cover, Back cover, stator, stand, and top cover.
Commands used: Sketch, revolve, extrude boss, cut extrude, pattern.
Motor parts are designed separately and then assembled using mates.
GEARBOX:
The most basic definition of a gearbox is that it is a contained gear train, or a mechanical unit or component consisting of a series of integrated gears within a housing. In fact, the name itself defines what it is — a box containing gears. In the most basic sense, a gearbox functions like any system of gears; it alters torque and speed between a driving device like a motor and a load. The gears inside of a gearbox can be any one of a number of types from bevel gears and spiral bevel gears to wormgears and others such as planetary gears. The gears are mounted on shafts, which are supported by and rotate via rolling element bearings. The gearbox is a mechanical method of transferring energy from one device to another and is used to increase torque while reducing speed.
Here I haven't shown the internal of the gearbox I just designed the external appeareance of it which consists the gear shaft for shifting the gears and pulley to transfer the motion through transmission belt.
DIFFERENTIAL:
A differential is a gear train with three shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others or a fixed multiple of that average.
In automobiles and other wheeled vehicles, the differential allows the outer drive wheel to rotate faster than the inner drive wheel during a turn. This is necessary when the vehicle turns, making the wheel that is travelling around the outside of the turning curve roll farther and faster than the other. The average of the rotational speed of the two driving wheels equals the input rotational speed of the drive shaft. An increase in the speed of one wheel is balanced by a decrease in the speed of the other.
Here I have joined the universal joint to the differential only.
A Universal joint is a joint or coupling connecting rigid rods whose axes are inclined to each other and is commonly used in shafts that transmit rotary motion. It consists of a pair of hinges located close together, oriented at 90° to each other, connected by a cross shaft. The universal joint is not a constant velocity joint.
Differential is also made out of different parts assembled together they are
Differential hub, gears, Differential cap, Hub, Washer, Universal joint.
Commands used: Surface revolve, Thicken, Sketch, circular pattern, boss extrude, Cut extrude, convert entities, Fillet, Chamfer and Mirror.
Tyre:
A Tyre is a ring-shaped component that surrounds a Wheels rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface travelled over. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, which also provide a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint that is designed to match the weight of the vehicle with the bearing strength of the surface that it rolls over by providing a bearing pressure that will not deform the surface excessively.
Tractors tyres are indifferent in size in front and back because a tractor is usually pulling things, the heavyweight behind it pushes the rear wheels down, increasing their grip by providing more contact and less slippage. The two smaller wheels at the front have a much better steering radius which means it's easier to turn sharp corners.
Rear tyre:
Rear tyres are usually huge because they need the most tractive power.
Front Tyre:
Commands used for the tyres are
Surface revolve, Thicken, Boss extrude, Cut extrude and Circular pattern.
FRONT BODY:
Here front body is the part of the tractor which covers the front motor part and front part of the tractor, here it also has headlights and the side indicators.
I have applied Amber led light for the headlights and red led for the indicators.
Commands : Surface extrude, Surface revolve, Surface loft, Surface fill, Boss extrude, Cut extrude, Linear pattern, Surface kint, fillet.
BACK BODY:
In this model, I have designed a back body with complete surface model and it even as a top cover from sun and rain protection. And applied glass material for sides.
Commands Used: Surface extrude, Thicken, Cut extrude, Mirror, Fillet, linear pattern.
Battery:
As I want to design the electric tractor it needs a heavy battery such that it can provide much torque when it is needed.
I added two main batteries to run the tractors and one mini battery for headlights, indicatrs.
one battery has 72 cells in it and other has 54 cells which are placed behind the seat and covered by the back body.
Battery 1:
Battery2:
Mini battery :
Battery placements:
Assembly:
At first, I have fixed chassis in the assembly area and then using coincident and distance mates I have placed motor in the front.
Next, I have placed gearbox to the chassis with using consistent mate.
By using concentric and width mates I have placed Transmission belt connecting the motor to the gearbox.
By using concentric mate differential is connected to gearbox.
Clamps are added to the gearbox shaft which connects to the chassis.
Front axle and front-wheel hub are connected using coincident and concentric mates.
Front tyre is connected using coincident and concentric mates and also added hexa bolts to it.
Rear tyre is connected to the differential hub and fender is connected to the chassis using coincident mate.
Front battery is placed using coincident, width mates.
Rear main batteries are placed using coincident and width mates.\
Front body is placed using distance, width, concentric and coincident mates.
Back body is placed using width and coincident mates.
Finally, steering is added using Concentric mate.
Final Preview:
Conclusion & Scope:
By Applying the solid and surface methodologies, design and assembly of mini tractor was completed using Solidworks 2018.
The project took 80Man hours to complete.
The idea behind the project is to demonstrate the design of the tractor by applying the Solidworks skills I have learned in this course.
Referance:
Wikipedia.